JP7375505B2 - Golf ball - Google Patents

Description

TECHNICAL FIELD The present invention relates to golf balls, and particularly to colored golf balls whose covers contain fluorescent pigments.

Golf balls are usually white in color. In the case of bad weather such as rain, cloudy weather, fog, or dim conditions, it is difficult to follow the trajectory of a white golf ball and visually recognize the landing point of the golf ball. Furthermore, if a white golf ball is stopped on dry grass, it is difficult to find the golf ball even if you are near the golf ball. In addition, the number of golf players who desire fashionable golf balls has recently increased. Under these circumstances, colored golf balls have been proposed in order to satisfy the demands for a fashionable appearance and visibility in bad weather.

For such colored golf balls, it is important that the dyes and pigments added have high coloring stability. Therefore, Patent Document 1 has a core and a cover that covers the core, the cover is formed from a resin composition containing a first base resin and a fluorescent pigment, and the fluorescent pigment is A fluorescent dye is dispersed in a second base resin, and the solubility parameter value (SP1) ((cal/cm ³ ) ^0.5 ) of the first base resin and the solubility parameter value (SP1) of the second base resin ( A golf ball is described in which the absolute value of the difference (|SP1-SP2|) from SP2) ((cal/cm ³ ) ^0.5 ) is 6 or less (see Patent Document 1 (Claim 1)).

Patent Document 2 discloses a colored golf ball that includes a core, a cover in which a large number of dimples are formed on the outer surface, and an inner layer in contact with the cover, in which: (i) a color difference ΔE between the inner layer and the ball; ^* is 30 or more; (ii) When expressed by the L ^* a ^* b ^* notation method based on JIS Z8729, the lightness L ^* value of the inner layer is 82 or more and is expressed as (a ^*2 + b ^*2 ) ^1/2 (iii) The brightness L ^* value of the ball is 50 or more; (iv) The brightness L ^* value of the ball ≦ the brightness L ^* value of the inner layer; (v) The transparency of the inner layer is completely transparent 10% or less, parallel transmittance 1.0% or less; (vi) A color golf ball is described in which the cover transparency satisfies the conditions of total transmittance 50% or more and parallel transmittance 1.0% or more (patent) (See Document 2 (Claim 1)).

Patent Document 3 describes a golf ball having a core, one or more cover layers covering the core, and a paint layer applied to the surface of the outermost layer of the cover. The paint layer is colored with a fluorescent pigment, and the color tone of the ball itself at a measuring hole diameter of 5 mm in the measuring method for reflective objects according to JIS Z 8722 is 30≦L, -40≦a≦60, in the Lab color system. A golf ball in which −20≦b≦60 is described (see Patent Document 3 (Claim 1)).

JP2018-102561A Japanese Patent Application Publication No. 2010-012250 Japanese Patent Application Publication No. 2010-246642

Colored golf balls have been proposed in the past, but there was room for improvement in the coloring stability of dyes and pigments. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a golf ball with excellent color stability.

The golf ball of the present invention that can solve the above problems has a core and a cover that covers the core, and the cover is formed from a resin composition containing a first base resin and a fluorescent pigment. It is characterized in that the number-based cumulative median diameter of the fluorescent pigment is 2.5 μm or more. When the number-based cumulative median diameter of the fluorescent pigment is 2.5 μm or more, the surface area per unit volume of the fluorescent pigment becomes small, and the contact area between the fluorescent pigment and the first base resin is reduced. Therefore, transfer of the fluorescent dye contained in the fluorescent pigment to the first base resin constituting the cover is suppressed, and the color development stability of the cover is improved.

According to the present invention, a colored golf ball with excellent coloring stability can be obtained.

1 is a partially cutaway sectional view showing a golf ball according to an embodiment of the present invention.

The golf ball of the present invention has a core and a cover that covers the core, and the cover is formed from a resin composition containing a first base resin and a fluorescent pigment, and the number of the fluorescent pigments is It is characterized in that the standard cumulative median diameter is 2.5 μm or more. When the number-based cumulative median diameter of the fluorescent pigment is 2.5 μm or more, the surface area per unit volume of the fluorescent pigment becomes small, and the contact area between the fluorescent pigment and the first base resin is reduced. Therefore, transfer of the fluorescent dye contained in the fluorescent pigment to the first base resin constituting the cover is suppressed, and the color development stability of the cover is improved.

[Resin composition for cover]
The cover resin composition contains a first base resin and a fluorescent pigment.

[Fluorescent pigment]
The fluorescent pigment is obtained by dispersing a fluorescent dye in the second base resin. The fluorescent pigment is preferably one in which a fluorescent dye is dispersed and fixed in the second base resin. Examples of fluorescent dyes fixed to the second base resin include fluorescent dyes fixed by using a thermosetting resin as the second base resin; fluorescent dyes fixed by reacting the fluorescent dye with the base resin. Things can be mentioned.

(Second base resin)
The second base resin is not particularly limited, and resins conventionally used for fluorescent pigments can be used, and thermosetting resins are preferable. Examples of the second base resin include benzoguanamine resin, acrylic resin, and polyester resin. The second base resin is preferably at least one resin selected from the group consisting of benzoguanamine resin, acrylic resin, and polyester resin, and more preferably benzoguanamine resin. The second base resin may be used alone or in combination of two or more.

Benzoguanamine resin Examples of benzoguanamine resins include condensates of benzoguanamine and formaldehyde.

Acrylic resin Examples of the acrylic resin include polymers of acrylic esters or methacrylic esters. Examples of the acrylic ester polymer include polymethyl acrylate, polyethyl acrylate, and polybutyl acrylate. Examples of the methacrylic acid ester polymer include polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, and the like.

Polyester Resin The polyester resin is not particularly limited as long as it has a plurality of ester bonds in the main chain of the molecule, and for example, one obtained by reacting a dicarboxylic acid and a diol is preferable.

[Fluorescent dye]
The fluorescent dye may be organic or inorganic, and may be any commercially available fluorescent dye. Examples of the fluorescent dye include thioxanthene derivatives, santhene derivatives, perylene derivatives, perylene imide derivatives, coumarin derivatives, thioindigo derivatives, naphthalimide derivatives, methine derivatives, and the like.

The fluorescent dye is not particularly limited, but specific examples include, by trade name, Lumogen F Orange.TM. 240 (manufactured by BASF); Lumogen F Yellow.TM. 083 (manufactured by BASF); Hostasol Yellow.TM 3G (manufactured by Hoechst-Celanese); Oraset Yellow.TM. 8GF (manufactured by Ciba-Geigy); Fluorol 088.TM. (manufactured by BASF); Thermoplast F Yellow.TM. 084 (manufactured by BASF) ;Golden Yellow .TM. D-304 (manufactured by DayGlo); Mohawk Yellow.TM. D-299 (manufactured by DayGlo); Potomac Yellow.TM. D-838 (manufactured by DayGlo); Polyfast Brilliant Red.TM. SB (K eyestone company Examples include yellow fluorescent dyes such as

The fluorescent pigment preferably has a number-based cumulative median diameter (50% diameter, D50) (particle diameter corresponding to cumulative 50% in a number-based cumulative distribution with the small diameter side being 0%) of 2.5 μm or more. is 2.6 μm or more, more preferably 2.7 μm or more, particularly preferably 3.0 μm or more. If the cumulative median diameter is 2.5 μm or more, the surface area per unit volume of the fluorescent pigment will be small, and the contact area between the fluorescent pigment and the first base resin will be reduced, so that color development stability will be improved. Further, the cumulative median diameter is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 50 μm or less, particularly preferably 20 μm or less. If the cumulative median diameter is 100 μm or less, the particles of the fluorescent pigment will not be too large and the color development will be stable.

The fluorescent pigment preferably has a number-based 10% diameter (D10) (particle diameter corresponding to cumulative 10% of the number-based cumulative distribution with the small diameter side being 0%) of 1.3 μm or more, more preferably 1. .4 μm or more, more preferably 1.5 μm or more, and if the 10% diameter is 1.3 μm or more, aggregation of the fluorescent pigment is suppressed and color development becomes good.

The fluorescent pigment preferably has a number-based 90% diameter (D90) (particle diameter corresponding to cumulative 90% in a number-based cumulative distribution with the small diameter side as 0%) of 250 μm or less, more preferably 230 μm or less, More preferably, it is 200 μm or less, particularly preferably 30 μm or less. If the 90% diameter is 250 μm or less, the particles of the fluorescent pigment will not be too large and the dispersibility of the fluorescent pigment will be good.

The difference (D90-D10) between the 10% diameter (D10) and 90% diameter (D90) is preferably 0.5 μm or more, more preferably 1.0 μm or more, even more preferably 2.0 μm or more, and 10 μm. The thickness is preferably below, more preferably 8.0 μm or less, still more preferably 6.0 μm or less. If the difference (D90-D10) is within the above range, the particle distribution of the fluorescent pigment will be stable and the moldability of the cover composition will be excellent.

The number-based mode diameter of the fluorescent pigment is preferably 2.0 μm or more, more preferably 2.2 μm or more, even more preferably 2.3 μm or more, and preferably 100 μm or less, more preferably 80 μm or less, and even more preferably is 50 μm or less, particularly preferably 15 μm or less. If the mode diameter is 2.0 μm or more, the surface area per unit volume of the fluorescent pigment will be small, and the contact area between the fluorescent pigment and the first base resin will be reduced, so color development stability will be improved, and the mode diameter will be 100 μm or less. If this is the case, the particles of the fluorescent pigment will not be too large and the color development will be stable. The mode diameter is a particle diameter having a maximum value (mode) in a number-based frequency distribution graph.

The number-based cumulative median diameter (50% diameter), 10% diameter, 90% diameter, and mode diameter of the fluorescent pigment can be determined from the image obtained by photographing the powder of the fluorescent pigment used as a raw material with an electron microscope. can. Note that the particle size of the fluorescent pigment does not change even after the cover composition is prepared or after the cover is molded. , the particle size of fluorescent pigments can be measured.

The density of the fluorescent pigment is preferably 1.300 g/cm ³ or more, preferably 3.0 g/cm ³ or less, and more preferably 1.355 g/cm ³ or less. If the density of the fluorescent pigment is within the above range, separation of the fluorescent pigment from the base resin during cover molding is suppressed. Note that the density is the ratio of the mass of the fluorescent pigment to the volume occupied by that mass of the fluorescent pigment (mass/volume).

The shape of the particles of the fluorescent pigment is not particularly limited, and examples thereof include spherical, substantially spherical, elliptical spherical, substantially elliptic spherical, irregular shape, etc., and spherical or substantially spherical is preferable. If the particle shape is spherical or approximately spherical, the surface area per unit volume is small and the coloring stability of the cover is further improved.

The content of the fluorescent pigment is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, still more preferably 0.5 parts by mass or more, particularly The amount is preferably 1.0 parts by mass or more, preferably 10 parts by mass or less, more preferably 9 parts by mass or less, still more preferably 8 parts by mass or less, particularly preferably 5 parts by mass or less. If the content of the fluorescent pigment is within the above range, the fluorescent pigment has sufficient color development.

(First base resin)
The first base resin is not particularly limited, and resins conventionally used for golf ball covers can be used. Examples of the first base resin include polyurethane resin, ionomer resin, amide resin, styrene elastomer, and the like. The resin composition for the cover preferably contains at least one resin selected from the group consisting of urethane resins, ionomer resins, and amide resins as the first base resin. The first base resin may be used alone or in combination of two or more.

(Polyurethane resin)
The polyurethane resin is not particularly limited as long as it has a plurality of urethane bonds in the molecule, and for example, it is a product in which urethane bonds are formed in the molecule by reacting a polyisocyanate and a high molecular weight polyol. If necessary, it can be obtained by further carrying out a chain lengthening reaction using a chain lengthening agent such as a low molecular weight polyol or a low molecular weight polyamine. As the polyurethane resin, thermoplastic polyurethane is preferable.

The polyisocyanate component constituting the polyurethane resin is not particularly limited as long as it has two or more isocyanate groups, and includes, for example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and Mixture of 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI) , xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), paraphenylene diisocyanate (PPDI), and other aromatic polyisocyanates; 4,4'-dicyclohexylmethane diisocyanate (H ₁₂ MDI), hydrogenated xylylene diisocyanate ( One or a mixture of two or more of alicyclic polyisocyanates or aliphatic polyisocyanates such as H ₆ .

From the viewpoint of improving scratch resistance, it is preferable to use aromatic polyisocyanate as the polyisocyanate component constituting the polyurethane resin. By using an aromatic polyisocyanate, the mechanical properties of the resulting polyurethane are improved, and a cover with excellent scratch resistance can be obtained. Additionally, from the perspective of improving weather resistance, non-yellowing polyisocyanates (TMXDI, XDI, HDI, _H6XDI , IPDI, _H12MDI , NBDI, etc.) are used as the polyisocyanate component constituting the polyurethane resin. It is preferred to use 4,4'-dicyclohexylmethane diisocyanate (H ₁₂ MDI). This is because 4,4'-dicyclohexylmethane diisocyanate (H ₁₂ MDI) has a rigid structure, improves the mechanical properties of the resulting polyurethane, and provides a cover with excellent scratch resistance.

The polyol component constituting the polyurethane resin is not particularly limited as long as it has a plurality of hydroxy groups, and examples thereof include low molecular weight polyols, high molecular weight polyols, and the like. Examples of low molecular weight polyols include ethylene glycol, diethylene glycol, triethylene glycol, propanediol (e.g. 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, etc.), Dipropylene glycol, butanediol (e.g. 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2,3-dimethyl-2,3-butanediol, etc.) ), diols such as neopentyl glycol, pentanediol, hexanediol, heptanediol, octanediol, 1,6-cyclohexanedimethylol, aniline diol, bisphenol A diol; glycerin, trimethylolpropane, hexanetriol, etc. Triols: Tetraols or hexaols such as pentaerythritol and sorbitol can be mentioned.

Examples of high molecular weight polyols include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG); polyethylene adipate (PEA), and polybutylene adipate (PBA). ), condensed polyester polyols such as polyhexamethylene adipate (PHMA); lactone polyester polyols such as poly-ε-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols. It may be a mixture of at least two or more polyols.

The number average molecular weight of the high molecular weight polyol is not particularly limited, but is preferably, for example, 400 or more, more preferably 1,000 or more. This is because by setting the number average molecular weight of the high molecular weight polyol to 400 or more, the obtained polyurethane does not become too hard and the shot feel of the golf ball is improved. Further, the number average molecular weight of the high molecular weight polyol is not particularly limited, but is preferably 10,000 or less, more preferably 8,000 or less. The number average molecular weight of the polyol component can be measured, for example, by gel permeation chromatography (GPC) using polystyrene as a standard substance, tetrahydrofuran as an eluent, and two columns of TSK-GEL SUPERH2500 (manufactured by Tosoh Corporation). Bye.

Further, the polyamine constituting the polyurethane resin as needed is not particularly limited as long as it has at least two or more amino groups. Examples of the polyamine include aliphatic polyamines such as ethylene diamine, propylene diamine, butylene diamine, and hexamethylene diamine; alicyclic polyamines such as isophorone diamine and piperazine; and aromatic polyamines.

The aromatic polyamine is not particularly limited as long as at least two or more amino groups are bonded directly or indirectly to an aromatic ring. Here, "indirectly bonded" means that the amino group is bonded to the aromatic ring via, for example, a lower alkylene group. The aromatic polyamine may be, for example, a monocyclic aromatic polyamine in which two or more amino groups are bonded to one aromatic ring, or an amino acid in which at least one amino group is bonded to one aromatic ring. It may also be a polycyclic aromatic polyamine containing two or more phenyl groups.

Examples of the monocyclic aromatic polyamine include types in which an amino group is directly bonded to an aromatic ring, such as phenylene diamine, toluenediamine, diethyltoluenediamine, and dimethylthiotoluenediamine; Examples include a type bonded to an aromatic ring via a lower alkylene group. Further, the polycyclic aromatic polyamine may be poly(aminobenzene) in which at least two aminophenyl groups are directly bonded, or poly(aminobenzene) in which at least two aminophenyl groups are bonded via a lower alkylene group or an alkylene oxide group. May be combined. Among these, diaminodiphenylalkane in which two aminophenyl groups are bonded via a lower alkylene group is preferred, and 4,4'-diaminodiphenylmethane and its derivatives are particularly preferred.

The configuration of the polyurethane resin is not particularly limited, but includes, for example, a configuration of a polyisocyanate component and a high molecular weight polyol component; a configuration of a polyisocyanate component, a high molecular weight polyol component, and a low molecular weight polyol component; Embodiments in which the composition is composed of a polyisocyanate component, a high molecular weight polyol component, a low molecular weight polyol component, and a polyamine component; Embodiments in which the composition is composed of a polyisocyanate component, a high molecular weight polyol component, and a polyamine component, etc. be able to.

The slab hardness of the polyurethane resin is Shore D hardness, preferably 20 or more, more preferably 26 or more, preferably 55 or less, more preferably 52 or less, and even more preferably 49 or less. By setting the hardness of the polyurethane resin to 20 or more in terms of Shore D hardness, the cover composition does not become too soft and good repulsion performance can be obtained. Further, by setting the hardness of the polyurethane resin to 55 or less in Shore D hardness, the cover composition does not become too hard and has sufficient durability. Specific examples of the polyurethane resin include "Elastoran (registered trademark) 1195ATR, ET880, 1198ATR, 1154D, NY82A" manufactured by BASF Japan Co., Ltd.

(Ionomer resin)
The ionomer resin is a metal ion neutralized product of a binary copolymer of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms (hereinafter referred to as “binary ionomer resin”). ); from a metal ion neutralized product of a terpolymer of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α,β-unsaturated carboxylic acid ester. ionomer resin (hereinafter sometimes referred to as ternary ionomer resin); or a mixture thereof.

The olefin is preferably an olefin having 2 to 8 carbon atoms, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, etc., with ethylene being preferred. Examples of the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid, with acrylic acid or methacrylic acid being preferred.

The α,β-unsaturated carboxylic acid ester is preferably an alkyl ester of α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, more preferably an alkyl ester of acrylic acid, methacrylic acid, fumaric acid, or maleic acid. In particular, acrylic acid alkyl esters or methacrylic acid alkyl esters are preferred. Examples of the alkyl group constituting the ester include methyl, ethyl, propyl, n-butyl, isobutyl ester, and the like.

The binary ionomer resin is preferably a metal ion neutralized product of an ethylene-(meth)acrylic acid binary copolymer. The ternary ionomer resin is preferably a metal ion neutralized product of a terpolymer of ethylene, (meth)acrylic acid, and (meth)acrylic acid ester. Here, (meth)acrylic acid means acrylic acid and/or methacrylic acid.

The binary copolymer constituting the binary ionomer resin and the tertiary copolymer constituting the ternary ionomer resin are α,β-unsaturated having 3 to 8 carbon atoms in the copolymer. The content of the carboxylic acid component is preferably 4% by mass or more, more preferably 6% by mass or more, even more preferably 8% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably is 20% by mass or less, particularly preferably 15% by mass or less. If the content of the α,β-unsaturated carboxylic acid component having 3 to 8 carbon atoms is 4% by mass or more, the binary ionomer resin will have higher repulsion, and if the content is 50% by mass or less, the binary ionomer will be more repulsive. Improves the flexibility of the resin.

The metal ions that neutralize at least a portion of the carboxyl groups of the binary ionomer resin and/or ternary ionomer resin include monovalent metal ions such as sodium, potassium, and lithium; magnesium, calcium, and zinc; , divalent metal ions such as barium and cadmium; trivalent metal ions such as aluminum; and other ions such as tin and zirconium. The binary ionomer resin and the ternary ionomer resin are neutralized with at least one metal ion selected from the group consisting of Na ⁺ , Mg ²⁺ , Ca ²⁺ , and Zn ²⁺ . Preferably.

The degree of neutralization of carboxyl groups in the binary ionomer resin and ternary ionomer resin is preferably 15 mol% or more, more preferably 20 mol% or more, still more preferably 50 mol% or more, and 100 mol% or more. % or less, more preferably 85 mol% or less. If the degree of neutralization is 15 mol% or more, the resulting golf ball will have good resilience and durability. On the other hand, if the degree of neutralization is 100 mol% or less, the golf ball resin composition will have good fluidity (good moldability). Note that the degree of neutralization of the carboxyl group of the ionomer resin can be determined by the following formula.
Degree of neutralization of ionomer resin (mol%) = 100 x number of moles of neutralized carboxyl groups in the copolymer/total number of moles of carboxyl groups in the copolymer

The binary ionomer resin and ternary ionomer resin may be a previously neutralized ionomer resin, or may be a combination of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms. A binary copolymer and/or a terpolymer of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α,β-unsaturated carboxylic acid ester, and a metal compound. They may be used in combination. Further, the binary ionomer resin and the ternary ionomer resin may be used alone, or two or more types may be used in combination.

The metal compound is not particularly limited as long as it can neutralize carboxy groups, and examples thereof include magnesium hydroxide, zinc hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, and potassium hydroxide. , metal hydroxides such as copper hydroxide; metal oxides such as magnesium oxide, calcium oxide, zinc oxide, copper oxide; metal carbonates such as magnesium carbonate, zinc carbonate, calcium carbonate, sodium carbonate, lithium carbonate, potassium carbonate, etc. can be mentioned.

The binary ionomer resins include Himilan (registered trademark) 1555 (Na), 1557 (Zn), 1605 (Na), 1706 (Zn), 1707 (Na), AM7311 (Mg), AM7329 (Zn) (Mitsui)・Dow Polychemical Company) Mg), 7930 (Li), 7940 (Li), AD8546 (Li) (manufactured by DuPont); IOTEC (registered trademark) 8000 (Na), 8030 (Na), 7010 (Zn), 7030 (Zn) (manufactured by ExxonMobil) (manufactured by Kagakusha), etc.

The ternary ionomer resins include Himilan AM7327 (Zn), 1855 (Zn), 1856 (Na), AM7331 (Na) (manufactured by Mitsui Dow Polychemicals); Surlyn 6320 (Mg), 8120 (Na), Examples include 8320 (Na), 9320 (Zn), 9320W (Zn), HPF1000 (Mg), HPF2000 (Mg) (manufactured by DuPont); Iotec 7510 (Zn), 7520 (Zn) (manufactured by ExxonMobil Chemical Company), etc. It will be done.

Examples of the binary copolymer include Nucrel (registered trademark) N1050H, N2050H, N1110H, N0200H (manufactured by Mitsui Dow Polychemicals); Primacol (registered trademark) 5980I (manufactured by Dow Chemical), and the like. Examples of the terpolymer include Nucrel AN4318, AN4319 (manufactured by Mitsui Dow Polychemicals), Primacol AT310, AT320 (manufactured by Dow Chemical), and the like. Na, Zn, Li, Mg, etc. written in parentheses after the above trade name indicate the metal species of these neutralizing metal ions.

(Polyamide resin)
The polyamide is not particularly limited as long as it is a thermoplastic resin having a plurality of amide bonds (-NH-CO-) in the main chain of the molecule. Examples include products in which an amide bond is formed within the molecule by reacting with

Examples of the polyamide resin include aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 6T, polyamide 6I, polyamide 9T, polyamide M5T, and polyamide 612; poly-p-phenylene terephthal; Examples include aromatic polyamides such as amide and poly-m-phenylene isophthalamide. These may be used alone or in combination of two or more. Among these, aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 11, and polyamide 12 are preferred.

Specific examples of the polyamide resin are given by trade names, such as "Rilsan (registered trademark) B" commercially available from Arkema (for example, Rilsan BESN TL, BESN P20 TL, BESN P40 TL, MB3610, BMFO, BMN). BMN O TLD, BMN BK TLD, BMN P20 D, BMN P40 D, etc.), and Pebax (registered trademark) 2533, 3533, 4033, 5533 manufactured by Arkema.

(Styrenic elastomer)
As the styrene-based elastomer, an elastomer containing a styrene block can be suitably used. The styrene block-containing elastomer includes polystyrene blocks as hard segments and soft segments. A typical soft segment is a diene block. Examples of the components of the diene block include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. Butadiene and isoprene are preferred. Two or more components may be used in combination.

Styrene block-containing elastomers include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isoprene-butadiene-styrene block copolymer (SIBS), and SBS. Includes hydrogenated products, hydrogenated products of SIS, and hydrogenated products of SIBS. Examples of hydrogenated SBS include styrene-ethylene-butylene-styrene block copolymer (SEBS). Examples of hydrogenated products of SIS include styrene-ethylene-propylene-styrene block copolymer (SEPS). Examples of hydrogenated products of SIBS include styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS).

The content of the styrene component in the styrene block-containing elastomer is preferably 10% by mass or more, more preferably 12% by mass or more, and particularly preferably 15% by mass or more. From the viewpoint of the shot feel of the resulting golf ball, this content is preferably 50% by mass or less, more preferably 47% by mass or less, and particularly preferably 45% by mass or less.

The styrene block-containing elastomer includes an alloy of polyolefin and one or more selected from the group consisting of SBS, SIS, SIBS, SEBS, SEPS, SEEPS, and hydrogenated products thereof. It is presumed that the olefin component in this alloy contributes to improved compatibility with the ionomer resin. By using this alloy, the repulsion performance of the golf ball is improved. Preferably, an olefin having 2 or more and 10 or less carbon atoms is used. Suitable olefins include ethylene, propylene, butene and pentene. Particular preference is given to ethylene and propylene.

Specific examples of polymer alloys include "Tefa Block (registered trademark) T3221C, T3339C, SJ4400N, SJ5400N, SJ6400N, SJ7400N, SJ8400N, SJ9400N, SR04" manufactured by Mitsubishi Chemical Corporation. Other specific examples of styrene block-containing elastomers include "Epofriend A1010" manufactured by Daicel Chemical Industries, Ltd. and "Septon HG-252" manufactured by Kuraray.

(UV absorber, light stabilizer)
Since the fluorescent pigment has low photostability, the cover resin composition preferably contains an ultraviolet absorber or a photostabilizer. The ultraviolet absorber or light stabilizer is not particularly limited, and may be any commercially available product. Examples of the ultraviolet absorber include salicylic acid derivatives, benzophenone derivatives, benzotriazole derivatives, cyanoacrylate derivatives, triazine derivatives, nickel complexes, and the like. Examples of the light stabilizer include hindered amine derivatives.

Examples of ultraviolet absorbers of salicylic acid derivatives include phenyl salicylate, pt-butylphenyl salicylate, p-octylphenyl salicylate; examples of ultraviolet absorbers of benzophenone derivatives include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy Benzophenone, 2-hydroxy-4-octyloxybenzophenone, 2,2-dihydroxy-4,4'-methoxybenzophenone, etc.; as a UV absorber for benzotriazole derivatives, 2-(2'-hydroxy-5'-methylphenyl ) Benzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole , 2-[2-hydroxy-3,5-bis(α,α'-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, etc.; of cyanoacrylate derivatives Examples of ultraviolet absorbers include 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate and ethyl-2-cyano-3,3'-diphenylacrylate; examples of ultraviolet absorbers for triazine derivatives include 2-(4 ,6-diphenyl-1,3,5-triazin-2-yl)-5[(hexyl)oxy]-phenol, 2,4-bis(2-hydroxy-4-butyroxyphenyl)-6-(2, 4-bis-butyroxyphenyl)-1,3,5-triazine, 2-(4-{[2-hydroxy-3-(2'-ethyl)hexyl]oxy}-2-hydroxyphenyl)-4,6 -bis(2,4-dimethylphenyl)-1,3,5-triazine and the like. Specifically, "Sumisoap 130" and "Sumisoap 140" (both benzophenone-based ultraviolet absorbers) manufactured by Sumitomo Chemical Co., Ltd., and "TINUVIN 234" and "Tinuvin 900" manufactured by Ciba Specialty Chemicals. , "Tinuvin 326", "Tinuvin P" (all benzotriazole series), "Uvinul N-35" (cyanoacrylate series) manufactured by BASF, "Tinuvin 1577" and "Tinuvin 460" manufactured by Ciba Specialty Chemicals. ", "Tinuvin 405" (triazine type), etc. These ultraviolet absorbers may be used alone or in combination of two or more. Note that the ultraviolet absorbers that can be used in the present invention are not limited to these, and any conventionally known ultraviolet absorbers can be used.

Examples of light stabilizers such as hindered amine derivatives include bis(1,2,2,6,6-pentamethyl-4-piperidyl) {[3,5-bis(1,1'-dimethylethyl)-4-hydroxyphenyl] methyl}butyl malonate, 1-{2-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]ethyl}-4-[3-(3,5-di-t- Examples include butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, and the like. Specific examples include "Sanol LS-2626" and "Tinuvin 144" manufactured by Ciba Specialty Chemicals, and "JF-90" manufactured by Johoku Kagaku Kogyo Co., Ltd.

(Titanium oxide)
The cover containing the fluorescent pigment is preferably transparent or translucent, but the cover may also contain titanium oxide. By combining fluorescent pigments with small amounts of titanium oxide, translucent covers with vibrant colors are obtained. Since the titanium oxide has a high hiding property, the content of titanium oxide is preferably 0.001 parts by mass or more, more preferably 0.002 parts by mass or more, and 0.005 parts by mass, based on 100 parts by mass of the resin component. The above is more preferable, less than 0.5 part by weight is preferable, 0.45 part by weight or less is preferable, and even more preferably 0.3 part by weight or less. When the titanium oxide content is 0.001 parts by mass or more, a translucent cover with a bright color is obtained, and when the titanium oxide content is 0.5 parts by mass or more, the cover exhibits hiding properties. Tend.

(other ingredients)
In addition to the above-mentioned components, the resin composition also contains pigment components, zinc oxide, mass control agents such as calcium carbonate and barium sulfate, dispersants, anti-aging agents, optical brighteners, lubricants, light stabilizers, etc. It may be contained within a range that does not impair the performance of.

The resin composition for the cover is obtained, for example, by dry blending the first base resin, the fluorescent pigment, and additives blended as necessary. Alternatively, the dry blended mixture may be extruded into pellets. For dry blending, it is preferable to use, for example, a mixer capable of blending raw materials in the form of pellets, and more preferably a tumbler type mixer. For extrusion, a known extruder such as a single screw extruder, a twin screw extruder, a twin screw single screw extruder, etc. can be used.

[Golf ball]
The structure of the golf ball of the present invention is not particularly limited as long as it has a spherical core and a cover that covers the spherical core. The structure of the golf ball includes, for example, a two-piece golf ball having a single layer spherical core and a cover covering the spherical core; a spherical core including a center and a single intermediate layer covering the center; and the spherical core. and a multi-piece golf ball that has a spherical core consisting of a center and two or more intermediate layers that cover the center and a cover that covers the spherical core.

A known rubber composition (hereinafter sometimes simply referred to as "rubber composition for core") can be used for the core or center, for example, a rubber containing a base rubber, a co-crosslinking agent, and a crosslinking initiator. The composition can be shaped by hot pressing.

As the base rubber, it is particularly preferable to use high-cis polybutadiene having 40% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more of cis bonds that are advantageous for repulsion. The co-crosslinking agent is preferably an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms or a metal salt thereof, and more preferably a metal salt of acrylic acid or a metal salt of methacrylic acid. The metal of the metal salt is preferably zinc, magnesium, calcium, aluminum, or sodium, and more preferably zinc. The amount of co-crosslinking agent used is preferably 20 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of the base rubber. When an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms is used as the co-crosslinking agent, a metal compound (eg, magnesium oxide) is preferably blended. As the crosslinking initiator, organic peroxides are preferably used. Specifically, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy) Examples include organic peroxides such as hexane and di-t-butyl peroxide, and among these, dicumyl peroxide is preferably used. The blending amount of the crosslinking initiator is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the base rubber. It is 3 parts by mass or less.

Further, the core rubber composition may further contain an organic sulfur compound. As the organic sulfur compound, diphenyl disulfides, thiophenols, and thionaphthols can be suitably used. The blending amount of the organic sulfur compound is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably 5.0 parts by mass or less, and more preferably Preferably it is 3.0 parts by mass or less. The core rubber composition may further contain a carboxylic acid and/or a salt thereof. The carboxylic acids and/or salts thereof are preferably carboxylic acids having 1 to 30 carbon atoms and/or salts thereof. As the carboxylic acid, either an aliphatic carboxylic acid or an aromatic carboxylic acid (benzoic acid, etc.) can be used. The amount of the carboxylic acid and/or its salt is 1 part by mass or more and 40 parts by mass or less based on 100 parts by mass of the base rubber.

In addition to the base rubber, a co-crosslinking agent, a crosslinking initiator, and an organic sulfur compound, the core rubber composition further contains a weight adjuster such as zinc oxide or barium sulfate, an anti-aging agent, a colored powder, etc. as appropriate. Can be blended. The hot press molding conditions of the rubber composition for the core may be set appropriately depending on the rubber composition, but usually heating is performed at 130°C to 200°C for 10 minutes to 60 minutes, or heating is performed at 130°C to 150°C for 20 minutes. After heating for 40 minutes to 40 minutes, it is preferable to perform two-step heating at 160° C. to 180° C. for 5 minutes to 15 minutes.

When the spherical core has an intermediate layer, examples of the intermediate layer material include thermoplastic resins such as polyurethane resins, ionomer resins, polyamide resins, and polyethylene; Plastic elastomers; cured products of rubber compositions, and the like. Here, the ionomer resin is, for example, a copolymer of ethylene and an α,β-unsaturated carboxylic acid in which at least a part of the carboxyl groups is neutralized with a metal ion, or a copolymer of ethylene and an α,β-unsaturated Examples include a terpolymer of a saturated carboxylic acid and an α,β-unsaturated carboxylic acid ester, in which at least a portion of the carboxyl groups are neutralized with metal ions. The intermediate layer may further contain weight regulators such as barium sulfate and tungsten, anti-aging agents, pigments, and the like.

The method for forming the intermediate layer is not particularly limited, but for example, a method in which the composition for the intermediate layer is previously formed into a hemispherical half shell, two half shells are used to wrap a sphere, and pressure molded; Examples include a method in which the composition for the intermediate layer is directly injection molded onto the sphere to wrap the sphere.

When molding the intermediate layer by injection molding the intermediate layer composition onto a sphere, it is preferable to use upper and lower molding molds having hemispherical cavities. The intermediate layer can be formed by injection molding by protruding the hold pin, inserting and holding the covered sphere, then injecting the heated and molten composition for the intermediate layer, and cooling it to form the intermediate layer. can.

When molding the intermediate layer by compression molding, the half shell can be molded by either compression molding or injection molding, but compression molding is preferred. Conditions for compression molding the intermediate layer composition to form a half shell include, for example, a pressure of 1 MPa or more and 20 MPa or less, and a temperature of -20°C or more and +70°C with respect to the flow start temperature of the intermediate layer composition. The following molding temperatures can be mentioned. By using the above molding conditions, a half shell having a uniform thickness can be molded. An example of a method for molding the intermediate layer using half shells is a method in which a sphere is covered with two half shells and compression molded. The conditions for compression molding the half shell to form the intermediate layer include, for example, a molding pressure of 0.5 MPa or more and 25 MPa or less, and -20°C or more and +70°C with respect to the flow start temperature of the intermediate layer composition. The following molding temperatures can be mentioned. By using the above molding conditions, an intermediate layer having a uniform thickness can be molded.

In addition, the molding temperature means the maximum temperature that the surface of the recessed part of the lower mold reaches between mold clamping and mold opening. In addition, the flow start temperature of the composition was determined by testing the thermoplastic resin composition in pellet form using Shimadzu's "Flow Tester CFT-500" with plunger area: 1 cm ² , DIE LENGTH: 1 mm, DIE DIA: 1 mm, The measurement can be performed under the following conditions: load: 588.399N, starting temperature: 30°C, temperature increase rate: 3°C/min.

The diameter of the spherical core is preferably 34.8 mm or more, more preferably 36.8 mm or more, even more preferably 38.8 mm or more, and preferably 42.2 mm or less, more preferably 41.8 mm or less, and even more preferably It is 41.2 mm or less, most preferably 40.8 mm or less. If the diameter of the spherical core is 34.8 mm or more, the thickness of the cover will not become too thick and the resilience will be better. On the other hand, if the diameter of the spherical core is 42.2 mm or less, the cover will not become too thin and the function of the cover will be better exhibited.

The manner in which the cover is molded using the cover composition is not particularly limited, but the manner in which the cover composition is directly injection molded onto a spherical core, or the manner in which a hollow shell is molded from the cover composition, A mode in which a spherical core is covered with a plurality of shells and compression molded (preferably a method in which a hollow half shell is molded from a cover composition, the spherical core is covered with two half shells, and compression molded) can be mentioned. The golf ball body with the cover molded thereon is preferably taken out from the mold and subjected to surface treatments such as deburring, cleaning, sandblasting, etc., as necessary. Also, marks can be formed if desired.

The thickness of the cover is preferably 0.3 mm or more, more preferably 0.4 mm or more, even more preferably 0.5 mm or more, and preferably 2.0 mm or less, more preferably 1.5 mm or less, even more preferably It is 1.0 mm or less. If the thickness of the cover is 0.3 mm or more, it will be easier to mold the cover, and if it is 2.0 mm or less, the diameter of the core can be relatively increased, which will improve the repulsion performance of the golf ball.

The total number of dimples formed on the cover is preferably 200 or more and 500 or less. If the total number of dimples is less than 200, it is difficult to obtain the dimple effect. Furthermore, if the total number of dimples exceeds 500, the size of each dimple becomes small, making it difficult to obtain the effect of the dimples. The shape of the dimples formed (plan view shape) is not particularly limited, and may be a circle; a polygon such as a substantially triangular, substantially quadrilateral, pentagonal, or hexagonal; or other irregular shape; Alternatively, two or more types may be used in combination.

The golf ball with the cover molded thereon is preferably taken out from the mold and subjected to surface treatments such as deburring, cleaning, sandblasting, etc., as necessary. Moreover, a coating film or a mark can be formed if desired. The thickness of the coating film is not particularly limited, but is preferably 5 μm or more, more preferably 7 μm or more, preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. This is because if the film thickness is less than 5 μm, the coating film is likely to wear out due to continuous use, and if the film thickness exceeds 50 μm, the dimple effect will be reduced and the flight performance of the golf ball will be reduced.

The diameter of the golf ball of the present invention is preferably 40 mm to 45 mm. From the viewpoint of satisfying the standards of the United States Golf Association (USGA), the diameter is particularly preferably 42.67 mm or more. From the viewpoint of suppressing air resistance, the diameter is more preferably 44 mm or less, particularly preferably 42.80 mm or less. Further, the mass of the golf ball is preferably 40 g or more and 50 g or less. From the viewpoint of obtaining large inertia, the mass is more preferably 44 g or more, particularly preferably 45.00 g or more. From the viewpoint of satisfying USGA standards, the mass is particularly preferably 45.93 g or less.

FIG. 1 is a partially cutaway sectional view showing a golf ball 1 according to an embodiment of the present invention. Golf ball 1 has a spherical core 2 and a cover 3 that covers spherical core 2. A large number of dimples 31 are formed on the surface of this cover. A portion of the surface of the golf ball 3 other than the dimples 31 is a land 32. This golf ball 1 includes a paint layer and a mark layer on the outside of the cover 3, but illustration of these layers is omitted.

Hereinafter, the present invention will be explained in detail with reference to Examples. However, the present invention is not limited to the following Examples, and any changes or embodiments of the present invention may be made without departing from the spirit of the present invention. Included within the range.

[Evaluation method]

(1) Fluorescent Pigment Density Fluorescent pigment density was measured using an automatic true density measuring device (BELPycno, manufactured by Microtrac Bell Co., Ltd.). The measurement conditions were gas used: helium, sample chamber volume: 10 cm ³ , and measurement temperature: 23°C. The measurement was performed twice for one fluorescent pigment, and the average value was taken as the density of the fluorescent pigment.

(2) Pigment particle size A powdered fluorescent pigment was photographed using a scanning electron microscope. A circle was drawn along the shape of each pigment particle on the obtained image (viewing height: 17.1 μm, width: 25.6 μm), and the pigment particles were extracted. At least 100 particles were extracted. The particle size of the extracted particles was measured using image processing software (ImageJ), and a number-based cumulative distribution graph (frequency distribution obtained by dividing the particle size of 0 μm to 10 μm in a linear plot into 50) was created. The mode diameter, D10 (10% diameter), D50 (cumulative median diameter, 50% diameter), and D90 (90% diameter) were determined from the graph.

(3) Color stability (weather resistance)
A golf ball was placed in a super xenon weather meter, and the golf ball was irradiated with light for 24 hours. The indices L ^* , a ^* , and b ^* in the CIELAB display system of each golf ball were measured using a color difference meter ("CM-3500d", manufactured by Konica Minolta). The index differences ΔL ^* , Δa ^* , and Δb ^* before and after the light irradiation were determined, and the color difference ΔE was calculated using the following formula.
ΔE = [(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ] ^1/2

(4) Color stability (heat resistance)
The materials for the cover composition were dry blended, and a pelletized cover composition was obtained using a twin-screw kneading extruder. Extrusion was performed with a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L/D=35. The formulation was heated to 150-260° C. at the die of the extruder.
The obtained cover composition was heated at 240° C. at the die position of an extruder and injection molded onto a spherical core without residence to produce Golf Ball I (240° C., 0 minutes). Further, the obtained cover composition was heated at 240°C at the die position of the extruder and left there for 20 minutes, and then injection molded onto a spherical core to form a golf ball II (240°C, 20 minutes). Created.
The color of the cover of each golf ball was measured using a color difference meter ("CM-3500d", manufactured by Konica Minolta). The color difference values of golf ball I are L ^* ₀ , a ^* ₀ , b ^* ₀ , and the color difference values of golf ball II are L ^* ₁ , a ^* ₁ , b ^* ₁ , and the color difference (ΔE) was calculated from the following formula. .
△E = [(L ^* ₁ - L ^* ₀ ) ² + (a ^* ₁ - a ^* ₀ ) ² + (b ^* ₁ - b ^* ₀ ) ² ] ^1/2

[Production of golf ball]
(1) Preparation of core A spherical core with a diameter of 39.7 mm was made by kneading the rubber composition of the composition shown in Table 1 using a kneading roll and hot pressing at 170°C for 20 minutes in upper and lower molds having hemispherical cavities. Obtained.

The raw materials used in Table 1 are as follows.
Polybutadiene rubber: manufactured by JSR Corporation, high-cis polybutadiene "BR730" (cis-1,4-bond content = 96% by mass, 1,2-vinyl bond content = 1.3% by mass, Mooney viscosity (ML ₁₊₄₎ (100°C) = 55, molecular weight distribution (Mw/Mn) = 3)
Zinc acrylate: “ZNDA-90S” manufactured by Nissaku Technofine Chemical Co., Ltd.
Zinc oxide: “Ginrei R” manufactured by Toho Zinc Co., Ltd.
Titanium oxide: “A220” manufactured by Ishihara Sangyo Co., Ltd.
Diphenyl disulfide: manufactured by Sumitomo Seika Co., Ltd. Dicumyl peroxide: manufactured by NOF Corporation, "Percmil (registered trademark) D"

(2) Preparation of cover The materials shown in Table 2 were dry blended and mixed using a twin-screw kneading extruder to obtain a pellet-shaped cover composition. Extrusion was performed with a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L/D=35. The formulation was heated to 150-260° C. at the die of the extruder. The obtained cover composition was injection molded to a thickness of 1.5 mm onto the spherical core obtained as described above to produce a golf ball having a spherical core and a cover covering the core. .

The raw materials used in Tables 2 and 3 are as follows.
Urethane resin: manufactured by BASF Japan, Elastran (registered trademark) NY82A (polyurethane elastomer (polyol component; polytetramethylene ether glycol, polyisocyanate component; dicyclohexylmethane-4,4'-diisocyanate, chain extender; 1,4- butanediol) (Shore A hardness 82))
Himilan (registered trademark) 1555: Manufactured by Mitsui Dow Polychemicals, ionomer resin Himilan 1557: Manufactured by Mitsui Dow Polychemicals, ionomer resin Styrenic elastomer: Manufactured by Mitsubishi Chemical, Tefabloc (registered trademark) T3221C
Wax Master VD2: Manufactured by BASF Japan, lubricant Titanium oxide: Manufactured by Ishihara Sangyo Co., Ltd., "A220"
Zinc oxide: Manufactured by Panasonic, Panatetra (registered trademark) WZ-0501
JF-90: Manufactured by Johoku Chemical Co., Ltd., light stabilizer Epocolor FP3000: Manufactured by UKSEUNG CHEMICAL CO., LTD. (fluorescent pigment in which fluorescent dye is dispersed and fixed in benzoquanamine resin (condensation product of benzoguanamine and formaldehyde))
FX305: Manufactured by Shinroihi Co., Ltd. (fluorescent pigment in which fluorescent dye is dispersed and fixed in benzoguanamine resin (condensation product of benzoguanamine and formaldehyde))
FX305S: Manufactured by Shinroihi Co., Ltd. (fluorescent pigment in which fluorescent dye is dispersed and fixed in benzoguanamine resin (condensation product of benzoguanamine and formaldehyde))

As shown in Tables 2 and 3, golf ball No. 1 in which the cumulative median diameter based on the number of fluorescent pigments is 2.5 μm or more. Nos. 4 and 7 had excellent cover color stability.

1: Golf ball, 2: Spherical core, 3: Cover, 31: Dimple, 32: Land

Claims (5)

It has a core and a cover covering the core,
The cover is formed from a resin composition containing a first base resin and a fluorescent pigment,
The first base resin contains a urethane resin,
The fluorescent pigment is a fluorescent dye dispersed in a second base resin, the second base resin is a thermosetting resin,
The number-based cumulative median diameter of the fluorescent pigment is 2.5 μm to 100 μm ,
A golf ball characterized in that the fluorescent pigment has a density of 1.300 g/cm ³ to 1.355 g/cm ³ . It has a core and a cover covering the core,
The cover is formed from a resin composition containing a first base resin and a fluorescent pigment,
the first base resin contains an ionomer resin,
The fluorescent pigment is a fluorescent dye dispersed in a second base resin, the second base resin is a thermosetting resin,
The number-based cumulative median diameter of the fluorescent pigment is 2.5 μm to 100 μm,
The density of the fluorescent pigment is 1.300 g/cm ³ ～1.355g/cm ³ A golf ball characterized by: The golf ball according to claim 1 or 2, wherein the fluorescent pigment has a difference (D90-D10) between a number-based 10% diameter (D10) and a number-based 90% diameter (D90) of 0.5 μm to 10 μm. ball. The golf ball according to any one of claims 1 to 3 , wherein the second base resin is a benzoguanamine resin. The fluorescent pigment according to any one of claims 1 to 4, wherein the content of the fluorescent pigment in the resin composition is 0.1 parts by mass to 10 parts by mass based on 100 parts by mass of the first base resin. Golf ball.

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